Perform Optical Character Recognition (OCR) to convert the bitmap image of text to actual characters.
If your version of Acrobat Pro DC is relatively up-to-date, there’s a chance that a scanned document will automatically undergo OCR upon opening the file.
In Acrobat Pro DC, the manual OCR scan can be performed two ways:
Via the Edit tool set — clicking the Recognize Text checkbox will immediately begin the OCR process. (Use the settings link directly above it to fine-tune the scan settings.)
Or, the Enhance Scans tool set also contains a Recognize Text dialog that functions similarly to the Edit tool’s Recognize Text checkbox.